As multiple associations between genetic variations in the DEFB4A/DEFB4B gene cluster and asthma and atopy in children suggest a role of these genes in asthma and allergy development, we investigated if hBD-2, due to its known functional entities, could help to explain protection against asthma and allergy by farm exposure and consumption of unprocessed milk on these farms. This evidence concerns the gene DEFB4A and Allergy.